Drill head



y 29, 1951 w. H. EVANS 2,554,820

DRILL HEAD Filed Dec. 31, 1946 Fig.5. l5

- I IN V EN TOR. WILLIAM Hm [IT-ER EVANS ATTDRNEX Patented May 29, 1951 UNITED STATES PATENT OFFICE.

DRILL HEAD William Hooper Evans, St. Louis, Mo.

Application December 31, 1946, Serial No. 719,441

1 Claim. 1

The present invention relates to a drill or cutting head of the type used on mining drills of the auger type for drilling rock, shale, sandstone, coal, etc. The invention is especially directed to an improved bit and socket assembly for incorporation in a drill head, and has for an object to provide a bit and socket assembly in which the bit is held in the socket by the use of wedge means, which, when tightened, positively fixes the bit in the socket in a predetermined constant position.

In drill heads heretofore in use, employing wedge means for holding the bit in the socket, no means is provided for positively predetermining the position of the bit, so that the position of the several bits in a drill head relatively to each is apt to var to a considerable extent, particularly after repeated removal and replacement of the bits for sharpening. This variation in the bit positions is due to a great extent to the fact that in driving the retaining wedge into place the position of the bit is not fixed in the socket, and consequently moves with the wedge to a greater or less extent relatively to the socket. It also results from the fact that wear upon the wedge and upon the walls of the socket causes the bit to gradually set furl-her down in the socket as the wedge is driven into tight retaining relation. The usual drill head design includes a number of groups of bits, usually two to a group,

arranged around the axial center line of the drill head and positioned so that the bits have a forward or cutting angle, an outwardly divergent side angle, and a cutting crown angle, the latter being produced by the relation of the cutting edges of the bits to each other. In order to obtain maximum cutting efficiency the desired relation of the bits to each other should be maintained under constantly unvarying conditions, it being pointed out that variation in the position of the bits may cause certain of the bits to take the entire cutting load and become quickly dulled, while the'other bits perform little or no work. For the reasons stated above, this desirable condition has been practically unattainable by quick, easy and economical methods.

It is particularly proposed in the present invention to provide a socket having positive seating means for determining the position of insertion of the bit, and positive locking means for interlockingly engaging the bit to prevent any change in 'its position of insertion, such locking means being effectuated by means of a tapered wedge driven into the socket, the bit being thus positively fixed against any change in its position during the driving of the wedge The invention is especially directed to the bit and socket assembly and can be incorporated in separated fabricated socket units adapted to be welded or otherwise suitably secured to a drill head o it may be incorporated as an original integrally formed part of the drill head.

With the above and other objects in view, embodiments of the invention are shown in the accompanying drawings, and these embodiments will be hereinafter more fully described with reference thereto, and the invention will be finally pointed out in the claim.

In the drawings:

Fig. 1 is a front elevation of a socket unit according to the invention, and having a single bit connected thereto.

Fig. 2 is a side elevation thereof.

Fig. 3 is a top plan view.

Fig. 4 is a bottom plan view.

Fig. 5 is a vertical sectional view taken along the line 55 of Fig. 3.

Fig. 6 is a front elevation of a modified form of socket unit according to the invention, having two bits incorporated therein and disposed in the same plane.

Fig. '7 is a top plan view thereof.

Fig. 8 is a front elevation of another modified form of socket unit according to the invention, having two bits incorporated therein and disposed in oifset planes, the two bits being retained by a single wedge member disposed between them.

Fig. 9 is a side elevation thereof,

Fig. 10 is a top plan view.

Fig. 11 is a bottom plan view.

Fig. 12 is a front elevation of another modified form of socket according to the invention, having two assemblies substantially similar to the single-bit socket shown in Figs. 1 to 5 integrally connected together so that the two bits are in oifset planes.

Fig. 13 is a top plan view thereof.

Fig. 14 is a side elevation of a drill bit having socket units according to the invention incorporated therein, and also having a pilot bit employing socket units according to the invention.

Similar reference characters indicate corresponding parts throughout the several figures of the drawings.

Referring to the drawings, and more particularly to Figs. 1 to 5 thereof, the bit and socket assembly shown therein comprises a socket member ill, of generally rectangular block form, provided with a socket passage l l extending between its upper and lower ends, and having parallel front and rear walls and downwardly converging side walls. At the base of one of the converging side walls there is provided a stop shoulder [22, which may be integrally formed or may be formed of a separate piece welded or otherwise suitably secured in place. In upwardly spaced relation of the stop shoulder E2 the side Wall is provided with an inwardly projecting retaining lug 13, which may be in theform of a pin secured in a drilled hole in the side of the socket member, or may be an integrally formed extension.

The bit I l is formed of straight rectangular cross-section stock, and is provided with a cutting edge formed by a ground or otherwise suitably produced beveled surface It at the cutting end of the bit. In one side wall oi the bit there is provided a pocket ll for interlocking engagement by the lug I3, this pocket being spaced upwardly from the lower end of the bit an equal distance to the spacing of the lug E3 of the socket member from the stop shoulder E2. The crosssectional dimensions of the bit are such that its opposite front and rear Walls slidably fit the parallel front and rear walls of the socket passage ll, while the distance between its opposed side walls is less than the distance between the downwardly converging side walls of the passage by an amount substantially greater than the projection of the lug l3. As a result of this arrangement, the bit is adapted to be inserted downwardly in the passage, without interference by the lug It, to the point where its lower end engages the stop shoulder [2. When the bit is engaged with the stop shoulder 12 the pocket I? is in register with the lug l3 and the bit is shifted against the side Wall carrying the lug 13 so that the lug interlockingly engages the pocket. This is the predetermined constant position of the bit in the socket, and this position is retained by engaging the tapered wedge E8 in the passage between one side wall thereof and the side of the bit, the taper of the wedge being predetermined to correspond to the downward convergence oi the opposed surfaces of the socket and bit. The wedge may be firmly driven into place by a hammer or the like, without changing the predetermined constant position of the bit. The wedge is of sufficient length so that in its driven position it projects below the socket member, where it is preferably provided with a hole 59 in which a length of wire or a cotter pin 29 maybe inserted and suitably bent to retain the wedge against displacement due to vibration or blows accidentally applied to its lower end.

It will be understood that the pocket I"! may be a drilled hole, slot, or other equivalent pocket means, and that the pocket may be provided in the wall of the socket member while the lug is provided in the bit.

The external shape of the socket member is immaterial as long at it provides sufiicient clearance behind the cutting edge of the bit in its assembled relation in the drill head. While it is shown as a separately fabricated unit, which may be welded or otherwise suitably secured to the drill head, it may of course be integrally formed with the drill head. In the latter case, it will be understood that the illustration of the socket member in the drawing is to be considered simply as a part of the drill head, as distinguished from a separate unit to be attached thereto.

In the modified form of th invention shown in Figs. 6 and 7 the socket member i8 is provided with a socket passage ii of sufficient size to receive two bits and an intermediate wedge member, all disposed in the same plane. Each of the iii downwardly converging end walls is provided at its lower end with a stop shoulder I2 and with a retaining lug [3. The two bits are engaged with the passage ll by first inserting them downwardly clear of the retaining lugs l3 into engagement with the stop shoulders l2, and thereupon shifting them laterally into interlocking engagement with the retaining lugs, the wedge member W being thereupon engaged and driven between the two bits and retained by engaging a length of wire or cotter pin 20 in its lower end.

In the modified form of the invention shown in Figs. 8 to 11, the socket member Ifl is provided with a socket passage i l one half of which is in a plane offset from the plane of the other half so as to receive two bit members l4 disposed in offset planes. The downwardly converging end walls of the socket are each provided with a stop shoulder 12 at its lower end and a retaining lug E3. The oiiset portions of the passage ll overlap each other at their inner ends and are each provided with a wall 2! which is downwardly convergent with respect to its opposed side wall but is parallel to the side wall of the other portion of the passage. i'here is thus formed an intermediate space for receiving the single wedge member i8 which corresponds in width to the full width of the offset passage and serves to retain both bits in place.

In Figs. 12 and 13 there is shown a further modified form of bit and socket assembly in which two bits are provided in relatively widely ofiset planes, the socket member Ill comprising a pair of socket portions, each substantially similar to the single bit socket member shown in Figs. 1 to 5, and integrally connected in overlapped staggered relation.

It will be understood that in all of the embodiments of the invention the external shape of the socket member may be of any suitable design for its particular use, and that it may be fabricated as a separate unit or may be integrally formed upon a drill head. By way of example, ther is illustrated in Fig. 14 the manner in which a plurality of the bit and socket assemblies may be incorporated in a drill head. This drill head comprises a central shank 22 of square cross section, about which four of the units as shown in Figs. 6 and 7 are secured by welding or other suitable means. Spiral sections 23 are preferably welded or otherwise suitably secured to the shank for carrying out material to the thread of the auger, the shank extending below the end of these spiral sections for the purpose of being inserted in a socket provided at the end of the auger. A hole 24 is provided in the shank for receiving a retaining pin or the like. It will be understood that, instead of the shank, the drill head may be provided with a suitable socket for engagement by a shank provided on the end of the auger. At the outer end of the shank 22 there is shown a pilot bit assembly, preferably consisting of a shank member 25 inserted and secured in a suitable socket in the end of the shank 22, and having welded or otherwise secured thereto a pair of socket and bit assembly units, as shown in Figs. 1 to 5. It will be obvious that numerous designs of drill heads may be constructed, employing the various bit and socket assemblies of the invention, and that in the operation of such drill heads the predetermined constant position of each of the bits will insure maximum efiiciency in the cutting action of the drill head and greatly increased length of service. Lost time through the necessity for frequent re-bltting of drill heads is substantially reduced.

I have illustrated and described preferred and satisfactory embodiments of the invention, but it will be understood that changes may be made therein, within the spirit and scope thereof, as defined in the appended claim.

What is claimed is:

A bit and socket assembly for mining drill heads, comprising a socket part havin upper and lower end walls and a bit-receiving passage extending therethrough and open at its upper and lower ends and wherein at least two opposed side walls are downwardly convergent one to the other, stop means within said passage, a bit longitudinally received in said passage, laterally engaged with one of said walls and longitudinally engaged with said stop means to fix its position in said passage, and a tapered wedge longitudinally engaged in said passage between said bit and said other side wall to wedgingly retain said hit in engagement with said first mentioned side wall through longitudinal wedging movement of said wedge said wedge being of a length to project below the lower open end of said passage, and a transverse pin engaged through the lower projecting end of said wedge and engaged with said lower end wall to restrain upward movement of said wedge.

WILLIAM HOOPER EVANS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

